The following discussion of the prior art is intended to place the invention in an appropriate technical context and enable its advantages to be more fully appreciated. However, any references to prior art throughout this specification should not be construed as an express or implied admission that such art is widely known or is common general knowledge in the relevant field.
Various di-wheel vehicles, cycles and mobile platforms are known, with one of the better known implementations being the “Segway”™ personal transporter. Such vehicles or platforms typically incorporate a pair of wheels disposed in spaced apart relationship for co-axial rotation. An inner body, chassis or frame extends transversely between the wheels and is supported for rotation relative to the wheels about the same axis.
Key advantages of vehicles and platforms of this type include relative simplicity due to the absence of an independent steering mechanism, the compact nature of the design and the high degree of manoeuvrability. However, due to the absence of a third wheel, stability is an inherent challenge both statically and dynamically.
For many applications it is preferable for such vehicles to be statically stable. In order to ensure static stability, the centre of gravity of the body, chassis or frame, complete with payload, must be lower than the rotational axis of the wheels. This is usually achieved by mounting the chassis as low as possible relative to the rotational axis, and mounting the drive motors, batteries, structural members, other system components and if necessary additional counterweights as low as possible on, within or beneath the chassis. However, this inherently obstructs the space between the wheels and compromises ground clearance, thus rendering known vehicles of this type unsuitable in applications requiring relatively high levels of ground clearance. Moreover, the heavier the payload needed to be carried, and the higher centre of gravity of the payload, the lower the centre of gravity of the chassis structure must be, and hence the more the ground clearance must be reduced.
Ground clearance may be increased to some extent by increasing the outer diameter of the wheels. However, this inevitably gives rise to other design compromises in terms of overall vehicle size, weight, manoeuvrability and/or cost of manufacture.
It is an object of the present invention to overcome or ameliorate one or more disadvantages of the prior art, or at least to provide a useful alternative.